The overall objectives of this research are to understand the physiology of bacterial conjugation by continuing our exploration of the events proceeding in the donor and in the zygote. In the donor, events leading to conjugation are determined by conjugative plasmids; hence genetic and enzymatic analyses of such plasmids are together one of the main activities to be continued. In the zygote, recombination and repliconation are the two major processes of inheritance; hence genetic and enzymatic analyses of these processes will also be continued. In addition, certain related objectives may also be pursued. The hypothesized involvement of recombination in many particular phenomena of bacterial genetics gives a clue to the possible importance of this process for determining the response of bacteria to their environment. For example, repair of lesions in DNA produced by ultraviolet irradiation or treatment with alkylating agents and induction of prophage lambda may occur through the action of enzymes of proteins involved in recombination.